yes, that returns one row. The ordering of the resultant string is non-deterministic though (I just ran it and got "def,abc,ghi"), and that is likely fine for most people's use-cases (in fact Heman2 mentioned in in the first answer in this thread). However, if one is looking for ordering, it won't be suitable and they may need to resort to the array_join,transform,array_sort,array_agg,lambda answer I posted above. I was just complaining about the cumbersome nature of it and don't mean to belabor this thread.